The Allan deviation \(\sigma _y\) , can be obtained from the PSD of the displacement phase noise through the integral expression [1]}
\(\sigma _{y}^2 (\tau )=2 \int _{0}^{+\infty } S_{\phi x}(f) \frac{\sin ^4\left(\pi f \tau \right)}{\left( \pi f \tau \right)^2} \text{d}{f},\) 
